The present invention relates to the treatment of fabrics and, more particularly, to the treatment of fabrics with finishing agents such as coloring agents, wherein such agent is applied to the fabric in the form of a foamed composition.
In the commonly-assigned U.S. patent application Ser. No. 584,389, now U.S. Pat. No. 4,118,526, there is described a process and composition for the treatment of fabrics wherein a fabric finishing agent, such as a coloring material, soil release agent, durable press agent, fire retardant agent, and the like, is applied to a fabric in the form of a stable foamed composition containing the finishing agent. According to the invention of application Ser. No. 584,389, a composition comprised of a fabric finishing agent and a foam stabilizer is foamed with a suitable inert gas to a blow ratio, i.e., the ratio of the weight of a given volume of the unfoamed composition to that of the same volume of foamed composition, of from about 2:1 to about 20:1 to result in a highly stable foamed composition, containing the fabric finishing agent, having a foam density in the range of from about 0.5 gm/cc to about 0.05 gm/cc. The foamed composition is then applied to a fabric and eventually collapsed and forced into the fabric by the application of a mechanical force.
The process and compositions of application Ser. No. 584,389 represent a significant advance in the art of treating fabrics with various finishing agents since the amount of liquid medium utilized is significantly reduced as compared to conventional processing, and thereby, among other advantages, reducing costly liquid removal processes and processing difficulties associated with the large liquid absorption capacity of many fabrics.
The present invention is particularly directed to the application of a color containing foam composition and is designed to accurately maintain the blow ratio and minimize the amount of increase in the volume of the foamed composition containing the coloring agent during application to the fabric. For example, agitation of the foamed composition during application on the fabric, e.g., in a rotary printing screen, can incorporate additional air into the foamed composition and thereby decrease its density. The attendant decrease in foam density may cause a non-uniform application of the coloring agent on the fabric, and, in general, makes overall control of the desired concentration of coloring agent to be applied to the fabric difficult.
The foregoing difficulty is encountered in processes for printing fabrics with a foamed printing composition by means of engraved printing rollers or rotary screen printers. In these cases, and particularly in the case of rotary screen printers, the foamed composition is subjected to significant agitation in the presence of air and is therefore susceptible to volume increases during application to a fabric. Moreover, the resultant non-uniform printing (e.g., streaks, shading) is, of course, most noticeable in such case and is highly undesirable from an aesthetic viewpoint.
U.S. Pat. No. 2,971,458 to Kumins, et al., describes a textile printing process utilizing a foamed printing composition which is applied to the engravings of a printing cylinder. To avoid the tendency for the air content of the foam to increase due to repeated transfers, Kumins, et al. provide a specially designed device to prevent additional air from contacting the foamed printing composition in the vicinity of its contact with the printing cylinder.